One of the problems associated with solid propellant rocket motors is that of stresses produced in the propellant where it is normally bonded to the inner wall of the motor case. The stresses can be induced by physical shock loading, cure shrinkage, and temperature changes in the propellant or combustion caviety. Stresses from any of these sources can cause cracks and fissures in the propellant which can cause unusually high burning rates due to the increased burning area with possible resulting catastrophic failure and explosion or at the least excessive and uncontrolled thrust output.
This problem has long been recognized in the art and various solutions have been offered all of which have various shortcomings such as increased weight, difficulty in building and assembling the motor, and excessive number of parts adding to the expense and complexity of the motor, and propellant attachment mounts or fittings which may produce excessive local stresses in the propellant.